Abstract
The phosphorescent emitters used in organic light emitting diodes (OLEDs) play a crucial role for tuning the color and the luminescence intensity. The authors have investigated by scanning tunneling microscopy the adsorption of iridium(III) phosphorescent emitter molecules used in OLEDs on a partly oxidized Cu(110) surface. Surprisingly they find that 50% of the emitters have dissociated upon adsorption at the substrate. The findings suggest that the decrease in the lifetime of OLEDs, which are manufactured by vacuum vaporization technique, is due to the dissociation of emitter molecules present in the device. (c) 2006 American Institute of Physics.